A gas station attendant pumps gas at a gas station Friday, May 25, 2012, in Portland, Ore. The AAA auto club reports the average price of a gallon of gas in Oregon is $4.22 for the beginning of Memorial Day weekend. That's up 18 cents in the past month and 31 cents higher than a year ago. (AP Photo/Rick Bowmer) The Associated Press

Fourteen Oregon cities already have gas taxes, although only two in the metro area -- Tigard and Milwaukie -- assess the per-gallon charge. Multnomah and Washington counties also have three-cent and one-cent gas taxes, respectively.

No one in Portland has proposed a gas tax but clearly it's at least on the radar.

The question about a Portland gas tax popped up last month during a budget work session for the Bureau of Transportation, which has been lambasted in recent months for lacking a prioritized spending plan while city leaders have committed to big-ticket projects.

"There is not a good estimate" for how much the one-cent tax would raise, transportation officials wrote. "However, if you assume the County's $.03 raises $6.5 million and if the gas tax revenue would mirror the population split of the City to the County's total population - 80%, $.01 would raise $1.7 million. However, I believe that we would have to share this with the County. We would get 80% of $1.7 million or approximately $1.36 million."

Gas taxes are known to bring out opposition from station owners.

Opponents, particularly in the metro area, have argued that charging taxes in one city but not a neighboring jurisdiction could hurt local stations. Tigard's gas tax is three cents a gallon while Milwaukie's is two cents a gallon.